Why format JSON
API responses, logs, and config often arrive as one long line. Pretty-printing makes object nesting and array items readable for debugging and code review.
ComTools JSON Formatter (Tools/Json/Formatter) parses and beautifies JSON locally in the browser—nothing is uploaded.
Features
| Feature | Details |
|---|---|
| Indent | 2 spaces, 4 spaces, or Tab |
| Syntax highlight | Keys, strings, numbers, booleans/null |
| Line numbers & fold | Collapse { / [ blocks for large objects |
| File upload | Load a local .json text file |
| Errors | Shows parse error messages for invalid JSON |
Steps
- Open JSON Formatter.
- Paste JSON, upload a file, or click Sample.
- Pick an indent (default 2 spaces).
- Click Run / Format.
- Copy the pretty result from the editor.
Example
Minified input:
{"name":"ComTools","free":true,"tools":["json","excel"]}
2-space output:
{
"name": "ComTools",
"free": true,
"tools": [
"json",
"excel"
]
}
Common scenarios
| Scenario | Approach |
|---|---|
| Inspect API responses | Paste from DevTools / Postman |
| Readable configs | Upload .json → format → copy back |
| One-line output | Use JSON Minify |
| Validity only | JSON Validator |
| From Excel | Excel to JSON then format |
Formatter vs validator vs minify
| Need | Tool |
|---|---|
| Pretty indent & fold | JSON Formatter |
| Valid or not | JSON Validator |
| Smallest payload | JSON Minify |
| Diff two docs | JSON Compare |
Formatting runs JSON.parse first; failures mean you must fix syntax before beautifying.
Notes
- Standard JSON only (double-quoted keys)—trailing commas and single quotes fail.
- Very large files are better in a desktop editor; browsers have memory limits.
- Local processing suits sensitive payloads—avoid untrusted machines.
FAQ
Key order changed?
Engines usually preserve insertion order; do not rely on key order in protocols.
Sort keys alphabetically?
Not currently—stringify keeps parse order.
vs VS Code Format?
Instant web use with fold/highlight for quick paste debugging.